Added new-style formatter function.

Added class `StrMethodFormatter` which is identical to `FormatStrFormatter`
only for new-style ('{}'.format) formatting methods.
pep8 fixes
put in explicit field name for 2.6 compatibility.
removed izip import which was blowing up the python 3.x builds
Merge pull request #2461 from tacaswell/new_style_format_str

Added a new style string Formatter.